I'm a fellow graphic designer and I've used several different screen. The Apple LCDs are very nice; however, they are expensive and IMHO are not worth it.
At work I use a 19" widescreen Dell (forget the model #, its the current model the Dell website). The color may not be as rich (still excellent though), but the clairty of pixels and font is just the same. Reponse time, contrast all are about the same with the Dell counterpart.
At home I use a 17" Hercules Prophetview 920Pro. $500+ 3 years ago as it was one of the best 17" LCDs out there. It's still a good monitor, but for half the price and a bigger screen the Dells are great step forward with my home LCD.
I highly recommend a widescreen monitor. Makes it a breeze to have multiple windows open etc.
Since color accuracy is very important in your perfession I recommend not going for those cheaper LCDs since they are most likely 6-bit LCDs. 8-bit LCDs are what you are looking for.
6-bit LCDs - Cheaper, faster response rates (usually lower than 8ms), but prone to have lots of color inaccuracies and image artifacts. These monitors uses 6 bits of data to represents each color of blue, green and red. That means this type of monitor can produce 64 shades of each color (64 = 2^6). This translates to a total of 262,144 actual colors (64^3; or 64 x 64 x 64). That's not a lot of colors to work with. Interpolation is the process used to increase the number of colors that the LCD can show on the screen. Interpolation is basically a way to mathematical "guess" what a color should be. Since guessing is not 100% accurate this can lead to discoloration and artifacts. Some manufactures lists the number of colors at 16.2 million instead of 16.7 million for the 8-bit LCD monitors. But some manufacturers list this 6-bit LCDs as being capable of producing 16.7 million colors. Thus, blurring the line can tricking some consumers into thinking the monitor is better than it actually is.
8-bit LCDs - These monitors are more expensive than their 6-bit counterparts, and have typically slower response times (8ms or higher), but they have better color accuracy. These monitors can truly reproduce 16.7 million colors. Since 8 bits of data is used to represents blue, green and red, 256 shades of each color is possible (256 = 2^8 ). This translates to 16.7 million colors (256^3; or 256 x 256 x 256).
Eizo produces a line of professional LCD screen specifically for people in the graphic profession. These LCDs are sometime referenced as being capable of producing 10-bit colors which translates to 1024 shades of each color and can potentially reproduce about 1.07 billion colors. However, these are not true "10-bit monitors" and they are still listed as being capable of producing 16.7 million colors. These are 8-bt LCDs and I believe they use a bulit-in look up table to provide more color accuracy (different from the interpolation process). Needless to say, these are expensive monitors; generally in excess of $1,400.
I have no experience with Apple LCDs, nor have I done any research on them.